CVE-2016-3075: Stack overflow in _nss_dns_getnetbyname_r [BZ #19879]

The defensive copy is not needed because the name may not alias the
output buffer.

(cherry picked from commit 317b199b4aff8cfa27f2302ab404d2bb5032b9a4)
(cherry picked from commit 883dceebc8f11921a9890211a4e202e5be17562f)

diff --git a/ChangeLog b/ChangeLog
index 64a2746e2d00b5b0eb7f4ef8bb225fe15f825965..4a0461d3c35cfcc2da1375acb6e0cc9bba5781ad 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2016-04-01  Florian Weimer  <fweimer@redhat.com>
+
+       [BZ #19879]
+       CVE-2016-3075
+       * resolv/nss_dns/dns-network.c (_nss_dns_getnetbyname_r): Do not
+       copy name.
+
 2016-04-01  Stefan Liebler  <stli@linux.vnet.ibm.com>
 
        * sysdeps/s390/bits/link.h: (La_s390_vr) New typedef.

diff --git a/NEWS b/NEWS
index 674d21701d01b0b8b31fd3e2c62e799f205ecb69..a08f96bd199d0602b8e7226b83f4f996354163c0 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -9,7 +9,10 @@ Version 2.23.1
 
 Security related changes:
 
-  [Add security related changes here]
+* The getnetbyname implementation in nss_dns had a potentially unbounded
+  alloca call (in the form of a call to strdupa), leading to a stack
+  overflow (stack exhaustion) and a crash if getnetbyname is invoked
+  on a very long name.  (CVE-2016-3075)
 
 The following bugs are resolved with this release:
 
@@ -17,9 +20,12 @@ The following bugs are resolved with this release:
   [19758] Or bit_Prefer_MAP_32BIT_EXEC in EXTRA_LD_ENVVARS
   [19759] Don't inline mempcpy for x86
   [19762] Use HAS_ARCH_FEATURE with Fast_Rep_String
-  [19791] Assertion failure in res_query.c with un-connectable name server addresses
+  [19791] Assertion failure in res_query.c with un-connectable name server
+    addresses
   [19792] MIPS: backtrace yields infinite backtrace with makecontext
   [19822] libm.so install clobbers old version
+  [19879] network: nss_dns: Stack overflow in getnetbyname implementation
+    (CVE-2016-3075)
 
 \f
 Version 2.23

diff --git a/resolv/nss_dns/dns-network.c b/resolv/nss_dns/dns-network.c
index 2eb2f67e66a8a2f51240eed081944159ebc6aca3..8f301a706b30287a8f8fb270bae8adfca055aae2 100644 (file)
--- a/resolv/nss_dns/dns-network.c
+++ b/resolv/nss_dns/dns-network.c
@@ -118,17 +118,14 @@ _nss_dns_getnetbyname_r (const char *name, struct netent *result,
   } net_buffer;
   querybuf *orig_net_buffer;
   int anslen;
-  char *qbuf;
   enum nss_status status;
 
   if (__res_maybe_init (&_res, 0) == -1)
     return NSS_STATUS_UNAVAIL;
 
-  qbuf = strdupa (name);
-
   net_buffer.buf = orig_net_buffer = (querybuf *) alloca (1024);
 
-  anslen = __libc_res_nsearch (&_res, qbuf, C_IN, T_PTR, net_buffer.buf->buf,
+  anslen = __libc_res_nsearch (&_res, name, C_IN, T_PTR, net_buffer.buf->buf,
                               1024, &net_buffer.ptr, NULL, NULL, NULL, NULL);
   if (anslen < 0)
     {